Guild Wars 2

I have just bought a new pc and downloaded GW2. I soon noticed that objects appeared purple as well as some textures. I also noticed that attack animations such as explosions were purple and pixelated as well as fire. I then realised that many objects and bridges weren’t appearing and would just be invisible.
My OS is windows 7 pro and I’ve got an NVidia gtx 660 which as I’ve seen from other threads is having problems and quite frankly I don’t know what to do. I’ve just bought the expansion before realising that the graphics and textures weren’t how they are supposed to be. I’m not getting a new PC anytime soon and I’m not changing my graphics card as it works perfectly with every other game and simulation I run. Anet doesn’t seem to care at all to fix the problem which so many are having and I feel cheated and that I’ve wasted my money as the game is unplayable in its current state.
I’ve attached a couple of screenshots to show what it looks like if you haven’t seen examples already.

I have had guild wars for over a year now and stopped playing for a couple of months just after the heart of thorns expansion was brought out. I recently bought a new computer and downloaded GW2 and the Heart of thorns expansion but upon playing the game i noticed that there was large areas that were coloured purple and objects were also purple as well. not only are objects purple but fire and attack animations are also purple and pixelated. I also find that some objects and landscape features are also invisible such as bridges. I can’t find anyone reporting these issues anywhere and so I am wondering how to fix these issues.
Thanks MG.